Various NMR techniques have been used to solve the solution structures of a number of molecules. These include polysaccharide, metabolite of antiangiogenic drug O-chloroacetylcarbamoyl,fumagillol, acid catalyzed rearrangement products of deoxyoartemisinins, and covalent nucleoside adducts from diol epoxides of polycyclic aromatic hydrocarbons. We have analyzed 500 MHz NMR NOE spectra of a DNA duplex modified at the adenosine residue with a highly carcinogenic diol epoxide metabolite of benzo[a]pyrene. These NOE data in conjunction with computer spectral simulation and distance restained molecular dynamics calculation indicated that the modified dA5 adopts an unusual syn glycosidic torion angle and that the pyrenyl moiety intercalates between bases of dG13 and dG14 of the complementary strand. In an attempt to gain insight into the mechanism of the formation of the less receptive isomeric nucleosides by purine nucleoside phosphorylase, a number of N-7 isomers of ribo- and deoxyribo-nucleosides have been synthesized and their reaction products in the presence of the enzyme have been monitored by NMR.